The present invention relates to a collecting sound device with directionality, a collecting sound method with directionality and a memory product having a computer program recorded thereon, which can enhance a voice signal generated from a sound source in a predetermined direction and suppress noises including ambient voices when voice signals including voices, noises and the like from sound sources existing in a plurality of directions are inputted.
With the progress of computer technology in recent years, the accuracy of voice recognition has been rapidly improved. A great number of sound collecting devices have been developed for specifying the direction of a needed sound source in order to identify a needed voice from voices generated from sound sources existing in a plurality of directions and suppressing voices and the like generated from sound sources existing in other directions as noises in sound processing.
For example, in a sound source separating method disclosed in Japanese Patent Application Laid-Open No. 10-313497 (1998), the arrival time interval of an input signal of each of microphones composing an array is detected on a frequency axis so as to see from which sound source an arrived sound comes from and separate the frequency component of the sound spectrum. Conventional noise suppressing methods for separating an aimed voice signal, which can be implemented on a time axis or a frequency axis, are classified broadly into two systems of a synchronous addition system and a synchronous subtraction system.
In a synchronous addition system, a synchronous process and an addition process fitted to an aimed direction are performed for voice signals inputted from a plurality of microphones. An aimed voice signal is enhanced by the addition process and noises including the other voice signals can be suppressed in comparison. In the meantime, in a synchronous subtraction system, a synchronous process and a subtraction process fitted to directions in which sound sources other than an aimed sound source exist are performed for voice signals inputted from a plurality of microphones, so that noises including voice signals other than an aimed voice signal can be suppressed directly.